Souri



W. IVI. DAVIDSON.

HoPPE uus ARRESTER.

APPLICATION FILED NOV. 29, |918.

Patented Nov. 25, 1919.

ATTORNEY.

.L3-22net.

f To all whom t may concern WILLIAM M. DAVIDSON, ors'r. Louis,- iviissoimi, Assieivon To WILLIAMS PATENT CRUSHER 8a PULVEBIZER'CO., 0F ST. VLOUIS, MISSOURI, A CORPORATION OFYMIS- Y Be it known that I, WILLIAM M. `DAviD- soN, a citizen of the United States, residing at St. Louis, State of Missouri, havein- .vented certain new and ,useful Improvements in Hopper Dust-Arresters, of which the following is a specification. I l

This invention. relates to certain new and useful improvements in hopper dust arresters for reducingvmachines, the peculiarities of which will be hereinafter described and claimed. ,Y

.The main object-of my invention is to provide means whereby the hopper of arelducing machine used for pulverizing lime, coal and similar materials, may be prevented from discharging the dust of the ground material from said hopper while the coarse material is being fed thereinto.

In the accompanying drawing on which like reference letters indicate corresponding parts, Figure 1 represents a sectional elevation through a reducing machine exemplifying my invention; and Fig. 2 a partial plan view of the same.

The letter A designates the shaft of a rotor consisting of hammers B and hammer supports, such as rods C and disks D, mount- Y ed on said shaft,-said rotor coperating with a suitable cage EV located in the casing F of a reducing machine, that is provided with a hopper Gr and a cover H, preferably eccentric, as shown in Fig. 1.

In the operation-of machines of this class, trouble is experienced on vaccount of the blowing out through the hopper, of the dust from the finely ground or pulverized'material being reduced within the casing.

I have found by practical experiment that this trouble is mainly or wholly eliminated by the provisionof Va rectangular box directly adjacent to the hopper and extendino' across the width of the hopper from sideV to side of the said cover. This box is pref-V erably cast integrally with the cover but may be otherwise'formed. It is preferably rectangular and consists of sides I substantially in the same plane of the sides of the cover IPI, a back J extending vertically upward from the arched top of said cover, and

' makin an acute an le with said cover a vfront K provided with an inwardly turned lip L substantially parallel to the sloping bottom of the hopperGr, and a top M. I

Horriin nUsT-AaREsTER..

Application fiieaiiovember 29, isis. seriai'ivo.'264,632."AA

preferv to make'ithe.y lip adjustable vertically by means of a slot Z and bolt N therein', adapted to allow of the `adjustment ofy said 'lip up and down as indicated byvdot- Vted linesfin Fig. l. Itwill be observed that Ysaid lip/is substantially: in thelhorizontalV plane through the'rotor shaft .and tangent to the hammer circle and therefore a slight Specification of Letters Patent.V A Patented NOV; 25, 1919.

adjustment; up :and downv will not vary, to any appreciable extent, thedistance between the .path Yof thehammers "B and the innerV and-lowerend of said lip.` From my experience, I have found it yto be necessary that the inner end ofsaid lip bev directly adjacent to the path of .the hammers in order to produce thedesired effect. Fig. 1 shows by arrows below. the lip in said hopper, the action of the' airl currentsof dustwhen the lip is properly adjusted `andfthe proper proportions areobtained in said box. 'I-hat is to s ay,-I haveobserved the'dusty air current turning .over and over in circular motion and in a direction corresponding, at the bot# tom, tol the inward flow of material. Just above the surface of the inwardly flowing material and between the material and the circularly moving dust current below said lip, there is a clear space comparatively free from dust, as though theair from outside were being carried along and downwardly with the inflowingmaterial.

It is desirable that the dust be discharged through the cage with the ground material andv when an exhaust fan handles the ground up material there is Vlittle or no discharge of dust from the hopper of the machine. When an exhaust fan is not used my device is especially effective and desirable in preventing the discharge of'these dust currents at the hopper and causing themto be delivered through the grinding cage instead of out through the hopper.

YI have found it essential to the. desired workingof this dust arrester,that`the width j inches, the width of said box would be about 8 inches. I have found that if such box were made 6 inches in width (which is less than one half of the radius mentioned), the

Y desired effect is notobtained.-

the 8Y inches may 'be increased to perhaps 10 :inchesv withoutA materially affecting., .the

proper-'action of `said boX, so'that it .may Y be said that the Width Vof said boX may range between'onefhalf to two-thirds ofthe' radius' f ofthehanuner circles.

is in practice llfinches, or"substantially-the 1 structionwas preventedr from Vso doing. It

same dimension as the said radius; lliave applied this dustvarresterv to reducingmachines such as coal Crushers of thel Williams l p type,jand have even successfullyfpulverized burnt limevin such-.a'inachina andfeliminatedf all or practicallyallthe dust' that formerly, -inlother constructions, was blown out of the hopper, butin my improvedconf' isV evident that when pulverizing suchrnatef rial as burnt lime, the elimination of'dust jis'of great practical advantage, and I have portions however I havefollowed in my ownV endeavored 'to the best of my ability tov give the proportions ofthe box aboverdescribed', as representing the .successfuloutcomev of my experiments, although" not being' wholly able t0 explainfthe 'scientificl'reason v:for the etlicient workingjo't the-same. Such'jpropractice in the manufacturev of 'such machines,v and submit the same that others versed in the art may be ablerto produce similar results. V

I @lai-1111:.. 'f 1.V A-machine ofthe character. described,

comprising rotary hammers, a'casinghaving a side hopper inlet and cover, and a rec- ,.Ktangular box, open below, consisting of ver.

tical side and end'walls and a top, the ylower end of the front side wall being substan# tiallytangent toI-th'e hammer circlenear the central horizontal plane, ancl the.back side 4 wall being connected 'atan angleV with. the

cover,-'the horizontal width 'between said front'andbackwalls being not less than one halt the hammer radius, nor more thantwo thirds ot said radius, andthe vertical height bein stantially as described. f

g substantially equal to said radius, sub-' Infa machine ofthe character :described Y* having 'a side inlet hopper, the hereinV described rectangular boX located-ad]- acent said inlet, and open below, and'providedon its lower frontedge with a vertically extend;

ible inturned 'lip' located directly adjacent to the path of ,thel hammers Vnear the cenltral horizontal plane, and operable substan- .5;l

tiallytangent-fte the hammer circle, and means to effect such adjustment up and down past the 'ends 'of the hammers, substantially as described'.

In' testimony whereoflrV have .aliixed my signature. 'f Y L p l* M. DAVIDSON. 

